Precision has not always been associated with measurement. In fact, at the dawn of civilization, man began to use parts of the body to estimate dimensions, and in about 6,000 B.C. from such measurements, there evolved the inch, hand, span, foot, cubit, year and fathom – the first standards of measurement. Of course, the tools of the past did not demand great accuracy as most products were manually and custom made, so a fraction of an inch in one way or the other made little difference to satisfactory operation.
However, today’s mass production demands precision measuring because the parts in any product must be uniform to be interchangeable. Eli Whitney first conceived the basic idea of mass production through interchangeable parts, and it was only through improved methods of measurement and mechanically powered machines that would make mass production possible. There was tremendous growth in mass production of all types of goods during the 19th century. Yet, it was not until after the Civil War that machines and measuring tools approaching the accuracy of modern standards were developed.